Funding Cleantech ventures is a complex process. While the end-user economics has gained some visibility the funding for research is still not a very clear process. According to reports, cleantech research funding was of the tune of $48 billion last year with the govt funding half of it.
But, mainstream adoption of cleantech will only happen if it is customer driven. While adoption of cleantech initiatives on an implementation scale is happening (installation s of biomass, solar and wind) etc, the end users could also put pressure through shareholder activism. Shareholder activism is the force that will help companies justify the large investments that are required for cleantech funding.
Further, it is probably important to understand that most new research in cleantech is going to be incremental. Almost all major technologies have been explored at some time or the other. The climate change debate has just bought these technologies into focus and hence forced companies to come up incremental research to push forward consumer acceptance through better economics.
One of the possible ways to look at cleantech funding would be set up a global fund for each field of research with identified centers of excellence to pursue those technologies. The companies could continue to focus on commercial incremental ventures. But the large breakthrough initiatives would require massive scales of funding where pooling of resources makes sense.